I suggest you ...

Why are Free Trials tied to bank card??? And is it even legal (in Europe)???

Free Trial accounts appear to be linked to the bank card used in the subscription -- why a bank card is required for a free subscription is absurd and I even wonder how legal (under European law).

But once a bank card was used for a Free Trial that bank card is "black-listed" from Free Trial subscriptions for 12-months.

Even not thinking about the legal/privacy implications of of that, I've previously used a Free Trial to evaluate some Azure features and now wanted to evaluate Notification Hubs -- not allowed because I'm using the same bank card. It's a different account, but that doesn't matter.

If the purpose of the Free Trial is to provide a limited time for trying out features and evaluate their capabilities, why is it so hard to do so???